Bogstandards "Paddleducks" engine

[shred]

It Runs!

After a couple evenings dinking with it, tearing it down, smoothing it out, putting it back together, timing it and re-timing it, running it in on a drill and having it almost-run on air, I finally got it sorted.

It's kinda funny now.. I'd just torn it all the way down and polished and tweaked a little more on the crossheads and reassembled it and timed it yet again and as usual, it kicked when turned over by hand, but didn't run. This was getting tedious...

Then I went through re-timing it one more time (the built-up bolted together crankshaft is a bit of a nuisance when trying to get the thing going-- as soon as something binds, it throws the crank out and you have to fuss around re-setting the crank and the timing).

After I set one end eccentric, I moved down to the other end to set it's eccentric and for some reason hit the air valve on the way before I set it. PHIPHIPHIP.. WAITTAMINUTE! it turned over! Crap, I've been setting the eccentrics wrong. :'( No wonder it didn't want to run.

Here's the trick-- set each eccentric with it's corresponding crank webs on the same side of the engine as the other one is set. Seems so simple now, but for some reason I had it in my head that they needed to be set opposite from each other (the instructions, as usual, are correct, it was me that mis-remembered them on the way from the PC to the shop)

First Run Video

It's running a temporary manifold for testing and about 40 PSI as I've yet to make the control block. It's leaking air like a sieve as there's no packing, piston rings or sealant anywhere, but it runs along nicely. On 80 PSI it buzzes like mad.

 

[kvom]

Super! :bow:

 

[Blogwitch]

Nice one Shred,

With the cheesy grin, and your confidence boosted, you can now carry on and bling to your hearts content.

It does pay sometimes to read the instructions.

You are the first one to build and show it running on the web (other than myself), you can be very proud of yourself.


Blogs

 

[Maryak]

It Runs!

Great stuff Shred - congratulations :bow:

Best Regards
Bob

 

[shred]

Had some relatives in town and fired the CNC Taig up for the first time in ages to do a little project for work, so not much progress... just the steam control block made and blinged a little.

I find it much easier to do edge-y things like this by setting the corner rounder (or chamfer or whatever) running along the fixed jaw of the vise and flip the part around as needed to catch all the edges. I think I got that tip from 'Machine Shop Trade Secrets". Here I've already done one side and flipped the part to cut the other. The downside is you can't watch the cut, but it's more than made up for in convenience.

These are with the rounding bit (I think it's 1/8" round, but it's not written on the obtained-surplus bit) centered on the jaw and 2.25mm down in Z, though sometimes in my limited corner-rounding experience I've moved the Y a bit to get the effect right (on this engine I've been 'abusing' the corner rounders by making them make a router-like cut with flats leading to a quarter-round section, no doubt with a proper router-bit name like 'Roman Ogive with a Half Gainer' that I'm conveniently unaware of). Experimenting on some scrap first is recommended.

 

[shred]

No real engine progress lately.. I decided (on John's advice) I wanted bent tubing and have been sidetracked building Bogs' favorite tubing bender (and a whole lot of work-related late night conference calls to Asia that cut into my evening shop time. )

Pretty straightforward, though I simplified it a little and skipped a lot of the draw-filing. Whoever "Torus" is, he really likes his draw-filing (note there are a few dimensions missing and a couple incorrect metric->imperial conversions on the drawings-- if you build this one pay careful attention )

The most interesting part was making the rolls. I used a method of cutting half-round grooves taken from Frank Ford's FRETS pages-- it's a bit of a hack, but worked.

In summary, load a round bit of the appropriate diameter into a QCTP holder and using the QC height adjustment as the 'infeed', run the lathe in reverse (non-threaded chuck required) and cut on the bottom. A little rake helps but there's still no clearance, so cutting isn't great, but it worked ok-- cut a little, move it up, cut a little more until you get the depth you want.

Short length of hardened drill rod turned to size used as cutting bit

Sharpening and putting a bit of rake into the bit.. QC holder is upside down in this pic

(lathe is in reverse)

Making them with a RT and mill would probably be better... I'll try that when I get my RT going vertically.

 

[shred]

Used the new bender to crank out some plumbing for a bent-pipe manifold. Here it is mocked up-- nothing soldered in yet, the brass screws are just to make sure the pipes won't block the cross hole. Cutting little bits of bent pipe identically is sort of irritating... anybody know any good tricks for that? These pipes aren't quite identical, but I'm suspecting that silver-soldering and subsequent fitting will get them bent up some more anyway.

 

[kvom]

Interesting look with the bent tube and flat flanges. More things to think about. 8)

 

[rickharris]

http://nextday.diy.com/app/jsp/product/productPage.jsp?productId=21946 Shows a pipe cutter many DIY stores will have in the plumbing section - I have one that woks very well.

 

[shred]

Interesting look with the bent tube and flat flanges. More things to think about.

Bogs says the engine looks better with curvy pipe on it and I agree. I've not fallen in love with this particular bend set, so may try a few more options before soldering it all up.

http://nextday.diy.com/app/jsp/product/productPage.jsp?productId=21946 Shows a pipe cutter many DIY stores will have in the plumbing section - I have one that woks very well.

That one works well on thin-wall tube? The similar cheapy one I have is pretty useless for annealed thin-wall, just bending the heck out of the tube before cutting anything. I'll have to see if better quality ones work better or if an insert might help. Actually cutting the tube is only half the battle though-- getting the lengths all trimmed up identically gets tedious as well (I've been bending a longer bit of tubing, then trim to length). I'm now kicking around the idea of making a specialized clamp which might work.

 

[rickharris]

The one I linkes to is made to cut small diameter small bore heating pipe and I have cut thin brass tube down to 3 mm easily and cleanly - it makes a progressive cut - You tighten it up as you turn it round the pipe.

 

[Blogwitch]

Shred,

Try this method.


Blogs

 

[Maryak]

Good One Blogs :bow: :bow: :bow:

Best Regards
Bob

 

[shred]

Simple and works better than holding them next to each other.. Thanks

The drilled-pliers (another classic Bogs' tip) worked great to hold the bent bits up against my mini belt sander for final length adjustment.

 

[mklotz]

Bogs is right on about cutting small or thin copper/brass tube. A cutoff disk in a Dremel is the stress-free way to do it and, done carefully, produces a finished edge that needs not much more than a tiny bit of deburring.

You'll get much better results doing this job and many others if you build an accessory table for your Dremel to provide the necessary alignment. I detailed such a table in an earlier post...

http://www.homemodelenginemachinist.com/index.php?topic=414.0

 

[shred]

Bogs is right on about cutting small or thin copper/brass tube. A cutoff disk in a Dremel is the stress-free way to do it and, done carefully, produces a finished edge that needs not much more than a tiny bit of deburring.

You'll get much better results doing this job and many others if you build an accessory table for your Dremel to provide the necessary alignment. I detailed such a table in an earlier post...

http://www.homemodelenginemachinist.com/index.php?topic=414.0

Funny.. I have that page open on a browser tab right now.. left over from deciding yesterday if I wanted to go make one right away or wait until this project is over.. With only 8 tubing cuts and a previous tool-making digression most of last week, laziness won out, but it's in the 'things to make' box now.

 

[mklotz]

It's one of those "baseball diamond" fixtures - make it and the ideas for using it will come.

To that end, keep flexibility in mind while designing it and don't be too quick to cut off what looks like excess material unless it's really in your way - there's no telling what you may invent to hang on it down the line.

The paper thin, about 1" diameter, cutoff disks Dremel sells work really well but they're fragile as hell. The slightest twist while using and they fracture. Dremel now sells some reinforced (~ 2" diameter) disks that are much sturdier. In addition, they alleviate the interference problem when cutting long stock.

Also, I use mine all the time for sizing small machine screws. (It's more economical to buy bulk quantities of 1/2" length and cut them down to needed size.) There are endless possibilities for screw holders to be used in conjunction with the cutoff guide pictured in my writeup.

Be sure to show us your version when you get it built. I for one will be anxious to steal any clever details you might include in your design.

 

[shred]

Alas shop-time is becoming scarce these days, with competition season heating up and the shop heating up (95'F/35'C today ). We do have a very good (and cheap) wholesale bolt-and-screw store here that's about made me give up on cutting down machine screws unless I really need one now or really need an off-size. The Dremel-table is still on-plan for everything else it's good for.

Anyway for the past few weeks I've been faffing around soldering up the piping and control block.

I thought I would try tumbling the fire scale off after pickling in a vibratory tumbler.. that took forever and a day (well, several days), then I saw one of the joints wasn't complete and had to go re-solder it.. Not wanting to tumble again, it went into the microblaster and five minutes later, it was clean and while rather matte than shiny, plenty good enough. The bonus of being able to blast off some errant silver solder easily was handy too (if you bling-corner the block like I did, watch out-- some solder ran off down the bling-channels instead of going up the proper spouts and would have been very difficult to remove without the blaster.)

Here's a staged photo in the hearth (post-blasted block, not bolted to the engine, etc):

The burnt-looking torn piece under the block is a little scrap of 1/8" fiber paper. Sometimes called 'fiberfrax', it's a heat-resistant ceramic paper material with a binder that burns off and smells like burnt sugar. Available for a few dollars a square foot at glass shops catering to the glass fusing crowd (they call it 'fiber paper' of all things). I use it for molten glass and underneath torch work and it works well-- not even a smudge or flux drippings on the underlying block.

The bit of hex rod over on the side was used previously to prop the bent tubes on for soldering to the flanges; Since I bent then soldered the tube, the hex gave the off-end a place to sit still in proper orientation to the flange which was flat on the hearth.

 

[Blogwitch]

Roy,

You have done a great job on that silver soldering job, very professional indeed.

A thin sheet of almost any metal between the parts would do as a heat shield, as long as it is not touching the valve block.

The way to make the parts hold together by themselves is to very gently squeeze the end of the copper tubes to ever so slightly deform them. Then they should hold in their holes in the right position while you continue with the dastardly deed of soldering them up.

I must admit, they do look a lot better with the bent tubing, but if you remember it was designed for people who didn't own such a thing as a tubing bender.


Blogs

 

[shred]

Thanks Blogs. I did blast off some extra SS to clean it up

I used the fiber paper because I have it handy and resists temperatures over 2000'F, but thin metal would be good for this operation as well.

I squeezed the tube ends a little, but the flanges wanted to creep up the tubes and rotate when heated since I probably didn't squeeze them enough. Setting one end on a conveniently sized bit of hex was the quick solution.

Hopefully I'll get time to finish up the control valve before too much longer.